This invention relates to methods and compositions for containing particulate matter within open top receptacles including but not limited to open top hopper cars, trucks, piles, and similar storage and/or shipping containers. Treating a load of particulate material (and in particular coal and iron ore) with a binding agent (sometimes referred to as a crusting agent) to encrust a surface and thereby retain valuable material as well as prevent the spreading of dust from the particulate is known. Prior binding agents are described among other places in U.S. Pat. No. 5,441,566. These binding agents include latexes, petroleum products, and pine tar resins. Other binding agents include phenolaldehyde resin mixed with a polyisocyanate in the presence of a catalyst (described in U.S. Pat. No. 5,244,473), alkaline phenolic resin (described in U.S. Pat. No. 5,089,540), and styrene in a hygroscopic solvent (methyl ethyl ketone), polyvinyl acetate and water (described U.S. Pat. No. 5,487,764). Additional dust suppressants are described in U.S. Pat. Nos. 5,181,957 and 5,747,104, 5,648,116, US Published Patent Application 2009/0189113 A1, and Published PCT Applications 02/12574 A1, 2010/110805 A1 and 2009/023652 A1.
Unfortunately many of these binders cause the particulate material to retain large amounts of water which can lead to diminished value and effectiveness. In the context of coal, increased water content results in decreased BTU content and increased likelihood of spontaneous combustion from water induced oxidation of the coal. Furthermore the binders tend to form brittle coatings which tend to shatter and dissipate as the particulate material settles and shifts due to the effects of transit and storage. Problems due to the brittleness of the binder coatings become exacerbated when the material is stored in environments where the temperature fluctuates above and below freezing. This is because freezing and melting moisture further shifts the materials further shattering the binder coating.
Prior art binding materials also have a number of winter handling problems that can render application difficult and potentially ineffective. This is because such products often have a freezing point near that of water and once frozen, they no longer work. Even worse these prior art binder coatings after being frozen are not recoverable even after they have thawed or melted if they have been frozen. This greatly limits the conditions in which they can be used and applied.
Thus it is clear that there is clear utility in novel methods and compositions for binding the top of particulate materials stored or shipped in open top containers. The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “Prior Art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 CFR §1.56(a) exists.